Ultrasonic welding is an industrial technique whereby high-frequency ultrasonic acoustic vibrations are locally applied to workpieces being held together under pressure to create a fusion weld. This technique is commonly used for joining similar and dissimilar materials. For example, dissimilar materials include thermoplastic polymers and metal (i.e., metal-polymers). Thermoplastic materials can be joined to metal with proper surface treatment of the metal. The technique is used in industries such as automotive, appliance, electronic, packaging, textile, and medical, among others.
Inconsistent weld quality results from factors including part and material variations. During ultrasonic welding, it can be difficult to determine online weld quality (e.g., weld quality as the weld is formed in real time or without removing workpieces from the welding system). In addition, certain welding systems are not equipped to make measurements to evaluate weld quality. Also, it can be difficult to create quality welds using a single-sided ultrasonic welding process, for example, because of a gap between workpieces.